There seems to be a difference in the way relativity views Planck length as frame dependent and the cosmological constant, an energy density?, as invariant....Any insights appreciated! There is a well known contradiction between relativity and the Planck length: Wikipedia explains the contradiction nicely: http://en.wikipedia.org/wiki/Double_special_relativity Yet the energy density of empty space is believed now to have a positive value and apparently this cosmological constant of "...universal energy density would have the same value for all observers, no matter where or when they made their observations no matter how they moved." (which is why Einstein called it "constant") Lee Smolin, THE TROUBLE WITH PHYSICS, 2006, P151. Or is the cosmological constant not quite like an energy density??